A common molluscicide; the main ingredient in certain fire lighters.


[affected.gif] Animals most affected
Dogs, cats (all other species).


[etiology.gif] Etiology
Accidental ingestion of granules containing 5-10% metaldehyde. Some major brands and certain formulations contain a cat and dog repellent. Accidental ingestion of the small white, rectangular-shaped artificial fuel briquettes, resembling sugar cubes, occurs especially when they are used for camping or for other outdoor activities. There is an increase in the number of cases of metaldehyde poisoning attributed to malicious use of the product in baits (most often meat-based baits).


[toxic.gif] Toxicity
A convulsant poison, the action of which is not fully understood. It is a gastric irritant.
Toxic doses in mg/kg
LD50  
 
rats 700
  guinea pigs 500
  rabbits
1250  
 
  dogs 500
 
cats  
 
500
  sheep 300
  goats 800
  pigs 400-500
  horses
300-400  
 
 
cattle  
 
400-500  
 


[clinical.gif] Clinical features
Presentation of symptoms 1-3 hours post-ingestion:

Note: occasional severe haemorrhagic diarrhoea with unobtrusive neurological effects.


[lesions.gif] Lesions
Non-specific:


[treatm~1.gif] Treatment
No antidote. Symptomatic care only:


If indicated, sodium phenobarbital, 30 mg/kg (care with the cardiorespiratory depressant effect);

If within 2 hours of ingestion (and if convulsions controlled):


[labinv~1.gif] Laboratory investigations
Samples of:


[case.gif] Case summaries
A dog presented with haemorrhagic gastroenteritis and melaena, accompanied by hypersalivation and vomiting. Clinical examination revealed, amongst other symptoms, motor incoordination and classic clonic contractions (intermittent) occurring over a prolonged period. Pieces of metaldehyde were visible in the faeces. Treatment included the administration of a benzodiazepine (diazepam), and anti-emetic, a gastrointestinal antacid and Ringer's Lactate. Within a day, the condition of the dog had improved and there was a favourable outcome.
A dog was brought into a veterinary surgery with mild tremor of the limbs and profuse hypersalivation. A few minutes later, the animal started having severe convulsions, with paddling movements of the limbs; iv diazepam, 2 mg/kg, controlled the symptoms. Investigations revealed that the dog had ingested metaldehyde granules having first played with, and then torn, the packaging of the product.
A herd of 30 cattle presented as an emergency with hypersalivation, generalized tremor and convulsions. Twelve animals died within the first 48 hours. At autopsy, congestive and degeneralized lesions were noted in the liver, lungs and kidneys of all the animals. A kitten that had been given milk to drink from one of the cows itself presented with hypersalivation, mydriasis, tremor, convulsions and ataxia. Diarrhoea was also noted. Investigations revealed that all the cattle had access to sacks containing granules of 5% metaldehyde. A total of about 10kg had been ingested. Metaldehyde poisoning was confirmed by laboratory analysis. Symptomatic care was instituted which prevented the remainder of the herd becoming more severely affected.